Perforating gun with novel charge tube assembly

ABSTRACT

An apparatus for use with a perforating gun includes a charge tube and at least one endplate. The charge tube has a cylindrical wall, a first end, an upper opening formed proximate to the first end, and a lower opening formed proximate to the first end. The at least one endplate has a central insert having a first section projecting from a second section. The first section seats in the upper opening of the first end and the second section seats in the lower opening of the first end.

TECHNICAL FIELD

The present disclosure relates to devices and method for perforating a subterranean formation.

BACKGROUND

Hydrocarbons, such as oil and gas, are produced from cased wellbores intersecting one or more hydrocarbon reservoirs in a formation. These hydrocarbons flow into the wellbore through perforations in the cased wellbore. Perforations are usually made using a perforating gun loaded with shaped charges. The gun is lowered into the wellbore on electric wireline, slickline, tubing, coiled tubing, or other conveyance device until it is adjacent to the hydrocarbon producing formation. Thereafter, a surface signal actuates a firing head associated with the perforating gun, which then detonates the shaped charges. Projectiles or jets formed by the explosion of the shaped charges penetrate the casing to thereby allow formation fluids to flow through the perforations and into a production string.

Conventionally, a perforating gun is assembled by affixing a detonating cord to one or more shaped charges disposed along a charge tube assembly. Prior art charge tube assemblies use threaded connections or plastically deformable members to affix endplates to a charge tube. Such arrangements may be costly and time consuming to manufacture and assemble.

Thus, there exists a need for devices that are less time consuming to manufacture and assemble. The present disclosure addresses these and other needs of the prior art.

SUMMARY

In aspects, the present disclosure provides an apparatus for use with a perforating gun. The perforating gun may have a tubular carrier, a charge tube, and an endplate. The charge tube is disposed in the carrier. The charge tube has a wall, a lower end, an upper opening formed proximate to the lower end, and a lower opening formed proximate to the lower end. The endplate engages the charge tube with the carrier. The endplate has a central insert formed by an upper section projecting from a lower section, wherein the upper section seats in the upper opening of the lower end and the second section seats in the lower opening of the lower end.

In aspects, the present disclosure provides a method for using a perforating gun in a wellbore. The perforating gun has a tubular carrier, a charge tube, and an endplate. The method includes the step of forming the perforating the perforating gun and conveying the perforating gun into the wellbore. The forming may be done by at least by laterally engaging the endplate with the charge tube.

It should be understood that examples of certain features of the invention have been summarized rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will in some cases form the subject of the claims appended thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

For detailed understanding of the present disclosure, references should be made to the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals and wherein:

FIG. 1 schematically illustrates a side sectional view of a perforating gun according to one embodiment of the present disclosure;

FIG. 2 schematically illustrates an isometric exploded view of a charge tube assembly according to one embodiment of the present disclosure;

FIG. 3 schematically illustrates an isometric assembled view of the FIG. 2 embodiment and

FIG. 4 schematically illustrates an sectional side view of the FIG. 2 embodiment.

DETAILED DESCRIPTION

The present disclosure relates to devices and methods for facilitating the assembly and enhancing the reliability of wellbore perforating tools. The present disclosure is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present disclosure with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein.

Referring now to FIG. 1, there is shown a section of one embodiment of a perforating gun 100 in accordance with the present disclosure. For ease of discussion, devices such as shaped charges and detonating cords have been omitted. The perforating gun 100 may include a tubular carrier 102 that is shaped to receive a charge tube assembly 104. For example, the charge tube assembly 104 may be positioned inside the carrier 102 in a telescopic fashion. In one arrangement, the charge tube assembly 104 includes a charge tube 108, a upper endplate 110, and a lower endplate 112. The endplates 110, 112 may be used to align the charge tube 108 relative to the carrier 102. This alignment may be a relative circumferential and/or axial alignment. The endplates 110, 112 may also be used to maintain a predetermined annular gap between the charge tube 108 and the carrier 102. To facilitate assembly, the ends of the charge tube 108 have openings that receive engagement members formed on the endplates 110, 112 as described in greater detail below.

Referring to FIG. 2, there is shown the charge tube 108 and the endplates 110, 112. The charge tube 108 may be a tubular member having a upper end 114 and a lower end 116. Each end 114, 116 includes upper and lower openings 118, 120 and 122, 124, respectively, that penetrate through a wall 109 of the charge tube 108. The openings 118, 120 and 122, 124 may be positioned to be closer to the ends 114, 116 than a mid-point of the charge tube 108.

The upper endplate 110 may be shaped as a disk or circular plate and formed of a suitable material such as steel. In the illustrated embodiment, the upper endplate 110 has a central insert 130 that is bracketed by opposing wings 132. Spaces 134 separate the insert 130 and the wings 132. The central insert 130 may be a platen member having a perimeter defined by sides and edges in order to perform selected functions. The central insert 130 may have an upper section 136 that projects from a lower section 138. The upper section 136 is sized to be closely received in the opening 120 of the upper end 114. The lower section 138 is sized to be closely received in the opening 118 of the upper end 114. In this arrangement, the sections 136 and 138 have different widths, but in other arrangements they may have the same widths. The wings 132 extend partially around the outer surface of charge tube 108 and include one or more projections 140 that project radially inwardly. Each projection 140 seats within a complementary medial opening 142 formed at the upper end 114.

In some embodiments, the wings 132 may be sufficiently elastically deformable in order to bend radially outward while the upper endplate 110 is being connected with the upper end 114 and then contract to allow each projection 140 to seat within the adjacent opening 142. Thus, the flexibility of the wings 132 generates a gripping force that fixes the upper endplate 110 to the upper end 114. While a minimal or nominal amount of plastic deformation may occur, it is principally or mostly the elastic deformation that provides the gripping force.

The lower endplate 112 may also be shaped as a disk or circular plate and formed of a suitable metal such as steel or non-metal such as plastic. In the illustrated embodiment, the lower endplate 112 has a central insert 160 that is bracketed by opposing wings 162. Spaces 164 separate the insert 160 and the wings 162. The central insert 160 may have an upper section 166 that projects from a lower section 168. The central insert 160 may be a platen member having a perimeter defined by sides and edges in order to perform selected functions. The upper section 166 is sized to be closely received in the opening 124 of the lower end 116. The lower section 168 is sized to be closely received in the opening 122 of the lower end 116. In this arrangement, the sections 166 and 168 have different widths, but in other arrangements they may have the same widths. The wings 162 extend partially around the outer surface of charge tube 108 and include one or more projections 170 at or near a terminal end 173. Each projection 170 seats within a complementary medial opening 172 formed at the lower end 116. As discussed previously, the wings 162 may be sufficiently elastically deformable in order to expand while the upper endplate 110 is being connected with the lower end 116 and then contract to allow each projection 170 to seat within the adjacent opening 172.

It should be noted that the first and the second plates 110,112 may be formed as an integral body; e.g., formed out of one solid body.

The first and lower endplates 110, 112 may include variations that allow each to have different behavior or functionality. For example, the wings 132 of the upper endplate 110 may be radially thinner than the wings 162 of the lower endplate 112. Thus, the wings 132 can more easily flex radially than the wings 162. The relatively thicker wings 162 makes the lower endplate 112 a more rigid structure. The greater flexure of the endplate 110 allows the wings 132 to apply a gripping force sufficient to fix the endplate 110 to the charge tube 108. The greater rigidity of the lower endplate 112 allows the lower endplate 112 to act as an orienting structure for the charge tube assembly 104.

Referring to FIGS. 1 and 2, in one embodiment, the lower endplate 104 may include a key 180 formed on the second section 166. The key 180 may be a protrusion that slides along a keyway (not shown) formed along an inner surface of the carrier 102. In some gun arrangements, the carrier 102 may include scallops 181, which are reduced wall sections. Each shaped charge of such a gun arrangement is aimed at a scallop 181. By reducing the thickness of the metal through which a perforating jet formed by the shaped charges must pass, the effectiveness of the perforating jet is enhanced. The key 180 and complementary keyway arrangement may be used to appropriately align the charge tube assembly 104 with the scallops of the carrier 102.

Referring to FIGS. 1 and 3, in some embodiments, a connecting mechanism may be used to secure the charge tube 104 to the carrier 102. In one non-limiting embodiment, the securing member 190 may be formed as an annular C-shaped body that includes a first connector 192 and a second connector 194. The first and second connectors 192, 194 may be formed as hooks, fingers, tabs, or other suitable projections.

Referring to FIGS. 2 and 3, the lower endplate 112 may include a groove 196 for receiving the first connector 192 and the top section 166 of the endplate 112 may include a slot 198 for receiving the second connector 194. The first and second connectors 192, 194 may be formed complementary to the slot 196 and groove 198, respectively. It should be noted that the slot 196 and the groove 198 are merely non-limiting examples of openings, recesses, cavities, and other structural formations that may be used to physically engage with the securing member 190. As shown in FIG. 3, the first connector 192 nests within the slot 196 and the second connector 194 nests within the groove 198.

Referring to FIG. 4, the first connector 192 has a flexible end 193 extends radially beyond the diameter of the lower endplate 112 when relaxed. The flexible end 193 may be a tab, coil, bar, or other body or member that can flex radially outward and be compressed radially inward. In the relaxed state, the flexible end 193 rests within a groove 210 formed on an inner surface 212 of the carrier 102. During assembly, the flexible end 193 is compressed from the relaxed state to the compressed state upon contacting a shoulder 214 formed near a bore opening 216. Upon reaching the groove 210, the flexible end 193 flexes outward into the groove 210, which then fixes the charge tube assembly 104 to the carrier 102.

In some embodiments, the first and the lower endplates 110, 112 may incorporate structural differences that prevent the first and the lower endplates 110, 112 from being inadvertently switched during assembly. For instance, the central insert 130 of the upper endplate 110 may include a recess 131 (FIG. 2) in which a bar 121 (FIG. 3) seats. The bar 121 may be a bridging member that divides the opening 120 into two sections. Because the central insert 160 of the lower endplate 112 does not have a recess, the lower endplate 112 cannot be completely connected to the upper end 114. It should be understood that other variations in structural geometry may also be used in lieu of or in addition to the recess 131 and the bar 121.

Furthermore, some embodiments of the present disclosure may use only one endplate. For example, referring to FIG. 4, the upper endplate 110 may be eliminated and replaced with a spacer 218. The spacer 218 may be a ring, collar, sleeve, or other spacing member that supports and centers the upper end 114 of the charge tube 108. In some variants, the spacer 218 may be formed integrally with the carrier 102.

Referring to FIG. 2, it should be understood that the endplates 110, 112 may also include other features such as bores 210 and 212 for receiving a detonating cord retainer (not shown) and/or to accommodate equipment such as bearings, sleeves, electrical connections, etc. Likewise, the charge tube 108 may include openings 214 for receiving shaped charges (not shown).

Referring now to FIGS. 1-3, the assembly of the charge tube assembly 104 will be described. Unlike conventional charge tube assemblies in which endplates are attached by moving the endplates in a direction parallel to a longitudinal axis of the charge tube, the endplates 110, 112 are installed by inserting the endplates 110, 112 in a direction that is perpendicular to a longitudinal axis 113 of the charge tube 108. Endplate 110 is inserted laterally through holes 118 and 120 and endplate 112 is inserted laterally through holes 122 and 124. When fully inserted, the projections 140 of wings 132 engage the adjacent opening 142 and the projections 170 of wings 162 engage the adjacent opening 172. Next, the securing member 190 is attached by inserting the first connector 192 into the slot 196 and inserting the second connector 194 into the groove 198. At this time, portions of the wall 109 of the charge tube 108 are securely seated in the spaces 134 and 164 of the first and lower endplates 110, 112, respectively. Thereafter, the charge tube assembly 104 may be inserted into the carrier 102. As noted above the flexible end 193 flexes outward into the groove 210, which then fixes the charge tube assembly 104 to the carrier 102.

It should be appreciated that the charge tube assembly of the present disclosure has several advantages over the prior art. First, the charge tube and the endplates are threadless. By threadless, it is meant that there are no threaded connections used to connect the charge tube with the endplates. Furthermore, the charge tube and the endplates use only elastic engagement. By elastic engagement, it is meant that the material making up the endplates and charge tube are deformed only within their elastic range. No feature of the charge tube or the endplates are plastically deformed in order to form a principal means of a connection.

It should also be noted that the embodiments of the present disclosure are assembled without the endplates 110, 112 moving axially toward the charge tube 108. Rather, assembly uses a lateral or transverse movement when assembling the endplates 110, 112 with the charge tube 108.

The teachings of the present disclosure may be used in connection with a perforating gun system at a well construction and/or hydrocarbon production facility positioned over subterranean formations of interest. The facility can be a land-based or offshore rig adapted to drill, complete, or service the wellbore. The facility can include known equipment and structures such as a platform at the earth's surface, a wellhead, and casing. A work string suspended within the well bore is used to convey tooling into and out of the wellbore. The work string can include coiled tubing injected by a coiled tubing injector. Other work strings can include tubing, drill pipe, wire line, slick line, or any other known conveyance means. The work string can include telemetry lines or other signal/power transmission mediums that establish one-way or two-way telemetric communication from the surface to a tool connected to an end of the work string. A suitable telemetry system can be known types as mud pulse, electrical signals, acoustic, or other suitable systems. A surface control unit (e.g., a power source and/or firing panel can be used to monitor and/or operate tooling connected to the work string.

At the surface, the perforating gun may be assembled as described above. Thereafter, the perforating gun is coupled to an end of the work string. An exemplary gun train includes one or more guns or gun sets, each of which includes perforating shaped charges. The perforating gun is conveyed into the wellbore and positioned as desired, and then fired.

The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope of the invention. For example, while two wings are shown for each endplate, other embodiments may use only one wing or three or more wings. Additionally, terms such as “upper,” “lower,” and “medial” are used only for convenience and not intended to require any particular orientation or positional relationship. It is intended that the following claims be interpreted to embrace all such modifications and changes. 

1. An apparatus for use with a perforating gun having a tubular carrier, comprising: a charge tube disposed in the carrier, the charge tube having a wall, a lower end, an upper opening formed proximate to the lower end, and a lower opening formed proximate to the lower end; and an endplate engaging the charge tube with the carrier, the endplate having a central insert formed by an upper section projecting from a lower section, wherein the upper section seats in the upper opening of the lower end and the second section seats in the lower opening of the lower end.
 2. The apparatus of claim 1, wherein the endplate includes a space separating at least one wing from the central insert, wherein at least a portion of the wall seats in the space, and wherein the at least one wing includes a projection seated in a medial opening formed in the lower end.
 3. The apparatus of claim 1, wherein the charge tube has a upper end, an upper opening formed proximate to the upper end, and a lower opening formed proximate to the upper end; and further characterized by: a upper endplate having a central insert having an upper section projecting from a lower section, wherein the upper section seats in the upper opening of the upper end and the lower section seats in the lower opening of the upper end.
 4. The apparatus of claim 3, wherein the upper endplate includes a space separating at least one wing from the central insert, wherein at least a portion of the wall seats in the space, and wherein the at least one wing includes a projection seated in a medial opening formed in the upper end.
 5. The apparatus of claim 3, wherein the upper end upper opening includes a bar dividing the upper end upper opening and the upper endplate upper section has a groove in which the bar seats.
 6. The apparatus of claim 3, wherein further characterized in that the at least one wing of the endplate is radially thinner than the at least one wing of the upper endplate.
 7. The apparatus of claim 1, wherein the charge tube and the endplates are threadless.
 8. The apparatus of claim 1, wherein the charge tube and the endplates only elastically engage.
 9. A method for using a perforating gun in a wellbore, the perforating gun having a tubular carrier, a charge tube, and an endplate, the method comprising: forming the perforating gun at least by laterally engaging the endplate with the charge tube, wherein: the charge tube is disposed in the carrier, the charge tube having a wall, a lower end, an upper opening formed proximate to the lower end, and a lower opening formed proximate to the lower end, and the endplate orients the charge tube relative to the carrier after engagement, the endplate having a central insert formed by an upper section projecting from a lower section, wherein the upper section seats in the upper opening of the lower end and the second section seats in the lower opening of the lower end; and conveying the perforating gun into the wellbore.
 10. The method of claim 9, wherein the endplate includes a space separating at least one wing from the central insert, wherein at least a portion of the wall seats in the space, and wherein the at least one wing includes a projection seated in a medial opening formed in the lower end.
 11. The method of claim 9, wherein the charge tube has a upper end, an upper opening formed proximate to the upper end, and a lower opening formed proximate to the upper end; and wherein the perforating gun further includes a upper endplate having a central insert having an upper section projecting from a lower section, wherein the upper section seats in the upper opening of the upper end and the lower section seats in the lower opening of the upper end.
 12. The method of claim 11, wherein the upper endplate includes a space separating at least one wing from the central insert, wherein at least a portion of the wall seats in the space, and wherein the at least one wing includes a projection seated in a medial opening formed in the upper end.
 13. The method of claim 11, wherein the upper end upper opening includes a bar dividing the upper end upper opening and the upper endplate upper section has a groove in which the bar seats.
 14. The method of claim 11, wherein the at least one wing of the endplate is radially thinner than the at least one wing of the upper endplate.
 15. The method of claim 9, wherein the charge tube and the endplates are threadless.
 16. The method of claim 9, wherein the charge tube and the endplates only elastically engage. 